My DT770 and qudelix are primarily for watching movies.

You would need either a different amp/dac that receives optical or a different media source like a media PC to play media from/attach your qudelix.

But really you are wasting money by not just using Bluetooth to your qudelix. You’re not going to notice a difference, and from a technical perspective I’d be surprised if a high quality stereo BT transmission is the compression/quality bottleneck when streaming movies anyway.

At worst I would buy a standalone BT transmitter with higher BT standard/better radio if your TV is lacking.